1. Field of the Invention
The present invention relates to a storage means, and more particularly, to a cassette for receiving substrates. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for receiving wide mother substrates having large liquid crystal display panels formed thereon, thereby preventing deterioration of the mother substrates and effectively transporting the mother substrates in a working space.
2. Discussion of the Related Art
In order to improve yield, a method of fabricating a liquid crystal display device generally includes the steps of forming thin film transistor array substrates on a mother substrate, forming color filter substrates on the other mother substrate, and bonding both of the mother substrates to each other to form a plurality of liquid crystal display panels at the same time.
FIG. 1 illustrates a cross-sectional view of a first mother substrate having thin film transistor array substrates and a second mother substrate having color filter substrates, in which the first and second mother substrates are bonded to each other to form a plurality of liquid crystal display panels.
Referring to FIG. 1, in unit liquid crystal display panels, each of thin film transistor array substrates has a side protruding from each corresponding color filter substrate 2. The gate and pad data parts (not shown) are formed at the corresponding edges of the thin film transistor array substrate 1 that do not overlap the color filter substrate 2.
Hence, the color filter substrates 2 of the second mother substrate 30 are formed to be spaced apart from each other by a dummy area 31, which corresponds to the protruding portion of each thin film transistor array substrate 1 of the first mother substrate 20.
The unit liquid crystal display panels are arranged so as to maximize the use of the first and second mother substrates 20 and 30. Depending upon various models, the unit liquid crystal display panels are generally formed to be spaced apart from each other by an area amounting to the other dummy area 32.
After the first mother substrate having the thin film transistor array substrates 1 is bonded to the second mother substrate 30 having the color filter substrates 2, the liquid crystal display panels are individually cut by a cutting process. The cutting process of the liquid crystal display panels is generally separated from the bonding process due to a limitation in a working area.
Hence, the bonded mother substrates are sequentially stored in a receiving space of a cassette. Once the receiving space is filled with the bonded mother substrates, the cassette is transferred to carry out the cutting process of the liquid crystal display panels. A related art cassette for receiving substrates is explained in detail by referring to the attached drawings as follows.
FIG. 2 illustrates a plane view of a related art cassette for receiving substrates. As shown in FIG. 2, the related art cassette for receiving substrates includes a frame 100 having an opening at the front side and support pins 101 protruding from both sides of the frame 100 to support the mother substrates 102 received in the frame 100.
FIG. 3 is a layout of the related art cassette for receiving substrates illustrating that the mother substrate 102 is supported by the support pins 101. As shown in FIG. 3, three of the support pins 101 protruding from each of the two lateral sides of the frame 100 are spaced apart from one another. Hence, three pairs of the support pins 101 support the mother substrate 102.
Namely, three pairs of the support pins 101 protruding from both lateral sides of the frame 100 have the same height, thereby stably supporting one of the mother substrates 102. In addition, the support pins 101 protruding from both lateral sides of the frame 100 are arranged regularly to correspond to the number of the mother substrates 102 to be received.
For instance, in case of a cassette receiving twenty mother substrates 102, the support pins 101 having a 3×20 arrangement protrude from each of the two lateral sides of the frame 100 to face into the corresponding ones.
In order to dispose the mother substrate 102 in the frame 100, the mother substrate 102 is loaded on a robot arm 103 (shown in FIG. 2) and is then transferred into the frame 100 to be slightly higher than the support pins 101 provided in the receiving space. Subsequently, the robot arm 103 is lowered to locate the mother substrate 102 on the support pins 101.
Once the frame 100 is filled with the bonded mother substrates 102, the cassette is transferred to carry out the following cutting process. However, the cassette having the frame 100 filled with the mother substrates 102 is frequently on hold due to delays in the cutting process of the liquid crystal display panels.
When the cassette is on standby, there is no problem in fabricating a small-sized liquid crystal display panel, since the mother substrate is small in size. However, when fabricating a product having a large-sized liquid crystal display panel, a degradation may occur because the size of the mother substrate itself is increased.
Meanwhile, when fabricating a product having a small-sized liquid crystal display panel, a liquid crystal injection method is used. Herein, the liquid crystal injection method includes the steps of injecting liquid crystals after the fabricated liquid crystal display panels are cut into individual unit liquid crystal display panels. However, when the liquid crystal injection method is used for a large-sized liquid crystal display panel, a processing time of the liquid crystal injection method takes longer, thereby reducing productivity.
As a result, a liquid crystal dropping method has been proposed in fabricating a large-sized liquid crystal display panel.
The liquid crystal dropping method includes the steps of dropping liquid crystals on a plurality of thin film transistor array substrates fabricated on a first mother substrate or on a plurality of color filter substrates fabricated on a second mother substrate, bonding the first and second mother substrates to each other to form a plurality of liquid crystal display panels, and cutting the bonded mother substrates into individual unit liquid crystal display panels. Hence, the liquid crystal dropping method minimizes product degradation because it can be applicable to the large-sized liquid crystal display panel.
However, when a product having the large-sized liquid crystal display panel is prepared by using the liquid crystal dropping method, weight and size of the mother substrates are increased, thereby increasing the degradation of the liquid crystal display panels.
Namely, when a product having the large-sized liquid crystal display panel is prepared by using the liquid crystal dropping method, the size of the mother substrate 102 or the weight of the liquid crystal display panel formed with the liquid crystal (LC)-dropped bonded substrates increases. Hence, when the waiting time of the cassette is extended, either the mother substrate 102 or the liquid crystal display panel supported by the support pins 101 protruding from both lateral sides of the frame 100 may be deteriorated in a manner that the central portion of the mother substrate or the liquid crystal display panel bends down. Hence, patterns of the liquid crystal display panels on the mother substrates 102 may be damaged or deteriorated. As for the bonded substrates having the liquid crystals therein, the panel itself is degraded.
Moreover, as the weight of the mother substrate 102 or the liquid crystal display panel is concentrated on the support pins 101, the characteristics of the liquid crystals in the areas of the mother substrate 102 contacting with the support pins 101 are degraded, thereby causing a display failure of the product.
Hence, the related art cassette increases product deficiency and reduces productivity.